Sex determination and gonadal sex differentiation in the chicken model.

Sex determination and gonadal sex differentiation in the chicken model. Int J Dev Biol. 2018;62(1-2-3):153-166 Authors: Hirst CE, Major AT, Smith CA Abstract Our understanding of avian sex determination and gonadal development is derived primarily from the studies in the chicken. Analysis of gynandromorphic chickens and experimental chimeras indicate that sexual phenotype is at least partly cell autonomous in the chicken, with sexually dimorphic gene expression occurring in different tissue and different stages. Gonadal sex differentiation is just one of the many manifestations of sexual phenotype. As in other birds, the chicken has a ZZ male: ZW female sex chromosome system, in which the male is the homogametic sex. Most evidence favours a Z chromosome dosage mechanism underling chicken sex determination, with little evidence of a role for the W chromosome. Indeed, the W appears to harbour a small number of genes that are un-related to sexual development, but have been retained because they are dosage sensitive factors. As global Z dosage compensation is absent in birds, Z-linked genes may direct sexual development in different tissues (males having on average 1.5 to 2 times the expression level of females). In the embryonic gonads, the Z-linked DMRT1 gene plays a key role in testis development. Beyond the gonads, other combinations of Z-linked genes may govern sexual development, together with a role for sex steroid hormones. Gonad...
Source: International Journal of Developmental Biology - Category: Biology Tags: Int J Dev Biol Source Type: research